Question

If xy1 = 0 then prove that x3 y3  1 =3xy

Answer 1

HEY!!

if x+y+1 = 0 then prove that x3 + y3 + 1 =3xy

we know x+y+1=0

then x+y = -1

x+y+1 = 0

(x+y)3 = (-1)3

x3 + y3 +3xy(x+y) = -1

x3 +y3 +3xy(-1) = -1

x3 +y3 - 3xy = -1

x3 + y3 +1 = 3xy


PROVED

Answer 2

Hey there!

( x + y + 1 ) = 0

x + y = -1

Cubing on both sides,

x³ + y³ + 3xy ( x + y) = -1³

x³ + y³ + 3xy ( -1) = -1

x³ + y³ +1 = 3xy.

Hence proved!